building an ATLAS .so

Guys,
I just got a message in a help request wanting to know how to build ATLAS
into a .so instead of a .a. I've never done it, but I know some of you have.
If anyone wants to answer this, I'll point him at the web archive. If you
want to avoid going on record there (where the guy might send questions
directly to you), I can forward it on, without your @, instead. Anyway,
it might wind up helping me as well: adding a auto build to .so has been
on my agenda for a long time, and maybe someday I'll get to it . . .
Thanks,
Clint